Field of the Invention
The present invention relates to metal-casting molds made by three-dimensional printing and methods for making the molds.
Background of the Invention
The characteristics needed for molds into which molten metal is cast are well known in the art. For example, see U.S. Pat. No. 6,080,813 and the following United States published patent applications: 2010/0140823 A1 of Asano et al., 2011/0073270 A1 of Stötzel et al., 2011/0129387 A1 of Stancliffe et al., 2011/0220316 A1 of Fuqua et al., 2012/0126092 of Jattke, 2012/0217373 A1 of Ide et al., and 2013/0032689 A1 of Haanepen et al.
Three dimensional printing was developed in the 1990's at the Massachusetts Institute of Technology and is described in several United States patents, including the following United States patents: U.S. Pat. No. 5,490,882 to Sachs et al., U.S. Pat. No. 5,490,962 to Cima et al., U.S. Pat. No. 5,518,680 to Cima et al., U.S. Pat. No. 5,660,621 to Bredt et al., U.S. Pat. No. 5,775,402 to Sachs et al., U.S. Pat. No. 5,807,437 to Sachs et al., U.S. Pat. No. 5,814,161 to Sachs et al., U.S. Pat. No. 5,851,465 to Bredt, 5,869,170 to Cima et al., U.S. Pat. No. 5,940,674 to Sachs et al., U.S. Pat. No. 6,036,777 to Sachs et al., U.S. Pat. No. 6,070,973 to Sachs et al., U.S. Pat. No. 6,109,332 to Sachs et al., U.S. Pat. No. 6,112,804 to Sachs et al., U.S. Pat. No. 6,139,574 to Vacanti et al., U.S. Pat. No. 6,146,567 to Sachs et al., U.S. Pat. No. 6,176,874 to Vacanti et al., U.S. Pat. No. 6,197,575 to Griffith et al., U.S. Pat. No. 6,280,771 to Monkhouse et al., U.S. Pat. No. 6,354,361 to Sachs et al., U.S. Pat. No. 6,397,722 to Sachs et al., U.S. Pat. No. 6,454,811 to Sherwood et al., U.S. Pat. No. 6,471,992 to Yoo et al., U.S. Pat. No. 6,508,980 to Sachs et al., U.S. Pat. No. 6,514,518 to Monkhouse et al., U.S. Pat. No. 6,530,958 to Cima et al., U.S. Pat. No. 6,596,224 to Sachs et al., U.S. Pat. No. 6,629,559 to Sachs et al., U.S. Pat. No. 6,945,638 to Teung et al., U.S. Pat. No. 7,077,334 to Sachs et al., U.S. Pat. No. 7,250,134 to Sachs et al., U.S. Pat. No. 7,276,252 to Payumo et al., U.S. Pat. No. 7,300,668 to Pryce et al., U.S. Pat. No. 7,815,826 to Serdy et al., U.S. Pat. No. 7,820,201 to Pryce et al., U.S. Pat. No. 7,875,290 to Payumo et al., U.S. Pat. No. 7,931,914 to Pryce et al., U.S. Pat. No. 8,088,415 to Wang et al., U.S. Pat. No. 8,211,226 to Bredt et al., and U.S. Pat. No. 8,465,777 to Wang et al.
In essence, three-dimensional printing involves the spreading of a layer of particulate material and then selectively jet-printing a fluid onto that layer to cause selected portions of the particulate layer to bind together. This sequence is repeated for additional layers until the desired part has been constructed. The material making up the particulate layer is often referred as the “build material” and the jetted fluid is often referred to as a “binder”, or in some cases, an “activator”. Post-processing of the three-dimensionally printed part is often required in order to strengthen and/or densify the part.
Three-dimensional printing has been used in the past for making molds for casting metals. For example, see the following United States patents: U.S. Pat. No. 7,087109 B2 to Bredt et al., U.S. Pat. No. 7,332,537 B2 to Bredt et al., U.S. Pat. No. 7,531,117 B2 to Ederer et al., U.S. Pat. No. 7,955,537 B2 to Ederer et al., and U.S. Pat. No. 8,211,226 B2 to Bredt et al.
One difficulty with the prior art methods of using three-dimensional printing to produce casting molds is their complexity. In the art cited above, it is necessary to use a multi-component build materials. For example, the build material disclosed in U.S. Pat. No. 7,955,537 requires the build material to consist of a particulate material and a reactive material and the jetted fluid reacts with the reactive material. Another difficulty with the prior art is that the build material that goes into making the bed of layers but which is not in the printed part may not be reusable as a build material.